1. Field of the Invention
The present invention relates to a pod used to store and carry substrates or wafers, and particularly, to the structure of a pod that is easy to clean, a method of cleaning a pod, an apparatus for cleaning a pod, and an apparatus for processing substrates.
2. Description of the Related Art
Generally, substrates or wafers made of, for example, silicon (Si) are stored and carried in wafer cassettes during manufacturing. Each wafer cassette carries 13 or 25 wafers. The wafer cassettes with wafers are transferred between processing apparatuses such as film forming and etching apparatuses during manufacturing. A wafer/substrate transferring system that employs the wafer cassettes is called a cassette-to-cassette system.
FIG. 25A shows a conventional open-type wafer cassette 800. The cassette 800 consists of a top plate 820, a bottom plate 810, and three posts that support the top and bottom plates 820 and 810. The posts 830 have grooves for supporting wafers, and the post 840 serves as a stopper for preventing the wafers from dropping.
In place of such wafer cassettes, pods have been studied to store and carry substrates or wafers, to meet needs for highly integrated fine devices to be produced from the substrates or wafers.
FIGS. 25B, 25C, and 25D show pods presently studied. Each pod consists of a pod body and a cover. The pod body is a box having an opening for taking in and out wafers, and the cover closes the opening of the pod body. The pod of FIG. 25B has a bottom opening that is closed by a cover 920. The pods of FIGS. 25C and 25D have side openings that are closed by covers 921 and 922, respectively. The pods of FIGS. 25B and 25D store the conventional open-type wafer cassettes with wafers. The pod of FIG. 25C has grooves on the inner wall thereof, to directly hold wafers without a wafer cassette.
The pods are capable of storing and carrying wafers in a closed dust-free space, thereby improving the yield of semiconductor products to be produced from the wafers.
Recent wafers are large in diameter, size, and weight to improve productivity. For these large wafers, the conventional wafer cassettes involve a risk of dropping the wafers during carriage, and therefore, the pods are preferable for such large wafers.
The pods are advantageous in keeping dust-free environment for wafers and securing safe carriage. The pods, however, have some problems. This will be explained.
The open wafer cassettes can be washed while holding wafers. On the other hand, wafers stored in closed pods are unable to wash. To wash them, they must be taken out of the pods. This means that the pods themselves are rarely washed during wafer processing.
As a result, the insides of the pods are gradually contaminated. This deteriorates the cleanliness of wafers stored therein, thereby lowering the yield of semiconductor products to be produced from the wafers.
The pods may be washed separately from the wafers during wafer processing. To wash large pods that store 200-mm to 300-mm diameter wafers, a large washing tank is needed. FIG. 26A shows a washing tank 950 for washing a pod 911. The tank 950 must be larger than the pod 911, and if the pod 911 is large, the tank 950 must be very large. FIG. 26B shows a pod washing apparatus having a washing tank 960 and a dryer chamber 980. This apparatus is very large. In a limited space in a clean room, such a large apparatus is hardly acceptable.
An object of the present invention is to provide a pod that is easy to clean, a method of cleaning a pod, an apparatus for cleaning a pod, and a semiconductor processing apparatus having a pod cleaning system.
In order to accomplish the object, a first aspect of the present invention provides a pod for storing substrates, having a pod body provided with an opening for taking in and out the substrates, a cover removably attached to the opening, and a fixing unit for fixing the pod body and cover together to tightly close the pod body. The cover has an inlet for introducing fluid into the pod and an outlet for discharging the fluid from the pod.
The first aspect tightly closes the pod body with the cover, introduces a washing fluid into the pod through the inlet, and discharges the washing fluid from the pod through the outlet. This aspect needs no separate washing tank to clean the inside of the pod because it uses the pod itself as a washing tank.
A second aspect of the present invention provides a pod for storing substrates, having a pod body provided with an opening for taking in and out the substrates, a cover removably attached to the opening, and a fixing unit for fixing the pod body and cover together to tightly close the pod body. The pod body has an inlet for introducing fluid into the pod and an outlet for discharging the fluid from the pod.
The second aspect tightly closes the pod body with the cover, introduces a washing fluid into the pod through the inlet, and discharges the washing fluid from the pod through the outlet. This aspect needs no separate washing tank to clean the inside of the pod because it uses the pod itself as a washing tank.
A third aspect of the present invention provides a pod for storing substrates, having a pod body provided with an opening for taking in and out the substrates, a cover removably attached to the opening, and a fixing unit for fixing the pod body and cover together to tightly close the pod body. The cover is provided with a nozzle for jetting fluid into the pod and an outlet for discharging the fluid from the pod.
The third aspect tightly closes the pod body with the cover, jets a washing fluid into the pod through the nozzle, and discharges the washing fluid from the pod through the outlet. This aspect needs no separate washing tank to clean the inside of the pod because it uses the pod itself as a washing tank. The nozzle showers a washing fluid of high pressure into the pod, thereby improving the physical cleaning power of the washing fluid in the pod.
A fourth aspect of the present invention provides an apparatus for cleaning a pod for storing substrates. The apparatus has a cover and a discharge pump. The pod has an opening for taking in and out substrates. The cover is removably attached to the opening and has an outlet for discharging gas from the pod. The discharge pump is connected to the outlet of the cover.
The fourth aspect tightly attaches the cover to the pod and evacuates impurity gases from the pod through the outlet, thereby cleaning the inside of the pod.
A fifth aspect of the present invention provides an apparatus for cleaning a pod for storing substrates. The pod has an opening formed on one face thereof to take in and out substrates. The apparatus has a cover to be removably attached to the opening of the pod, an inlet formed on the cover to guide gas into the pod, an outlet formed on the cover to discharge gas from the pod, a gas supply source connected to the inlet of the cover, a gas adjuster arranged between the inlet of the cover and the gas supply source to adjust the flow rate of gas, a vacuum pump connected to the outlet of the cover, a pressure sensor for measuring a pressure in the pod, and a controller electrically connected to the gas adjuster, vacuum pump, and pressure sensor.
The fifth aspect sets a washed pod in the apparatus, evacuates remnants from the pod, and fills the pod with an inert gas.
A sixth aspect of the present invention provides an apparatus for processing substrates. The apparatus has a pod reception chamber, a pod processing chamber, a substrate processing chamber, and a transfer unit for transferring the pod and substrates between these chambers. The pod has an opening on one face thereof to take in and out substrates and a cover to be removably attached to the opening. The pod reception chamber has a unit for receiving a pod with substrates from the outside and a unit for taking the substrates out of the pod. The pod processing chamber has a unit for cleaning the inside of the pod. The substrate processing chamber has a unit for processing the substrates.
The sixth aspect cleans the inside of the pod in the pod processing chamber while processing the substrates in the substrate processing chamber.
The cover of the pod of the sixth aspect may have an inlet for guiding fluid into a pod and an outlet for discharging fluid from the pod. The unit for cleaning the inside of a pod may have a unit for fixing the opening of the pod and the cover together to tightly close the pod, a unit for introducing a washing liquid into the pod through the inlet of the cover, and a unit for discharging the washing liquid from the pod through the outlet of the cover. The cover may have a second outlet for discharging gas and a heater.
The unit for cleaning the inside of a pod may have a table for tightly closing the pod set on the table, an inlet formed on the table to introduce fluid into the pod, an outlet formed on the table to discharge fluid from the pod, a unit for introducing a washing liquid into the pod through the inlet, and a unit for discharging the washing liquid from the pod through the outlet. The table may have a second outlet for discharging gas and a heater.